Abstract

Effects of stages of growth and intercropping of two sweet potato varieties (Hawassi-83 and Tula) (alone or with coffee or maize-haricot bean) on biomass yield and in vitro dry matter digestibility (IVDMD) of morphological fractions were assessed in Southern Ethiopia. Similar coffee plantations (age, density, soil type, topography) were selected for intercropping. Vines were planted on three plots per intercropping type at 15 days interval, and cultivated three times. Morphological fractions were collected from 1.0 m² of land on 4th, 5th and 6th months for nutrient and partial budget analyses (revenue estimated for 100 m² of land). Ten elders evaluated varieties at 2nd, 4th and 6th months after planting. Lowest DM (77 g/kg) was obtained from fresh Tula stem-petiole (FTSP) but highest (190 g/kg) from fresh Tula leaf (FTL) (p<0.05). Fresh Tula vine (FTV) had lowest (840 g/kg DM) organic matter and FTL (p<0.05) highest (914 g/kg DM). Crude protein content of fresh Hawassi-83 stem-petiole (FHSP) was lowest (113 g/kg DM) but that of FTL highest (269 g/kg DM). Lowest vine yield (0.27 kg/m²) was from Tula intercropped with coffee but highest (0.82 kg/m²) from maize-haricot bean intercropping followed by sole Hawassi-83 (0.56 kg/M²). Overall mean vine DM yield (333.6 g/m²) of maize-haricot bean intercropping was greater (p<0.05) than that of intercropping (174.0 g/m²) with coffee. IVDMD of fresh Hawassi-83 leaf (FHL) (78.0±0.27) and FTSP (77.0±0.10) were lowest but that of FHSP (84.3±0.59) and FTL (84.3±0.04) highest. Both Hawassi-83 and Tula vine were best produced when intercropped with maize-haricot bean, although Hawassi-83 was more profitable and preferred by respondents than Tula.

Key words: Intercropping, morphological fractions, nutrients, stage of maturity, sweet potato vine.